•Provide a mechanism for selecting restoration and

management projects based on ecological value,

sustainability and cost

•Create an approach to conservation, restoration and

management that can be used in urban natural areas

•Create indices of health to monitor the effectiveness of

restoration and management over time

•Use data and research to strengthen public policy and

programming that support conservation

•Strengthen conservation partnerships and infuse data-

driven decision making into planning and management.

Citywide Ecological Assessment: A Tool for Prioritizing Restoration and Management in New York City

Helen Forgione1, Clara Pregitzer1, Sarah Charlop-Powers1, Bram Gunther1,2

New York City has 10,000 acres of natural areas: forests,

wetlands, and meadows within the 30,000 city-park system.

There are another 20,000 acres of parkland managed by

federal, state, and other city entities (Figure 1). Natural areas

are defined here as lands that are specifically set aside,

protected, and managed to maintain biological diversity and

promote passive public recreation activities.

The Natural Areas Conservancy (NAC) was launched in 2012

as a not-for-profit working in partnership with the New York

City Department of Parks & Recreation (Parks) to protect,

restore, and manage the expansive natural areas within the

urban park system in New York City.

In 2013, the NAC initiated the first-ever citywide ecological

assessment of natural areas to guide the creation and

implementation of science-based decision-making tools to

achieve conservation goals.

1Natural Areas Conservancy, New York, NY

2Natural Resources Group, NYC Department of Parks & Recreation, New York, NY

Introduction

Characterizing New York City’s Natural Areas

Using Assessment Data to Inform

Management Preliminary Results

ACKNOWLEGEMENTS

Ecological Data was collected by the Natural Areas Conservancy and NYC

Department of Parks & Recreation, Natural Resources Group staff and

interns. Special thanks to New York City Parks for support. Thanks to

Nancy Falxa-Sonti and Rich Hallett with the USDA Forest Service Northern

Research Station for assistance with forest methods.

Generous Funding to support the Ecological Assessment was provided by

The Mayor’s Fund to Advance New York and the Tiffany & Co. Foundation.

sampling will produce a final

Ecological Community Map to

enable NAC and partners to

have more accurate and

detailed land-cover information

for various analysis, planning,

and decision-making activities,

such as natural resource

assessments, and

management and restoration

activities.

Developing the Framework for Sampling Methods

In the first year of a two year ecological assessment, upland/ forest

data was collected from four parks in Brooklyn and in Van Cortlandt

Park in the Bronx . Freshwater wetlands were evaluated in two parks

in the Bronx and Queens. Salt marsh data was collected in 17

complexes in Queens, Brooklyn, and the Bronx. Breeding bird

surveys were conducted in forests, grasslands, and salt marshes.

Together this work comprises 35% of natural areas in New York City.

In 2014, the remaining natural area habitats managed by Parks are

being assessed.

The initial data can be analyzed to compare unique habitat types and

parks across the landscape.

Key Ecological Attributes of Healthy

Forests

Indicators Measurement

Canopy dominated by native species Relative basal area of native tree

species

DBH, height, species of trees > 10 cm DBH

(Fixed-area plot sample)

Canopy closure or landscape

distribution of closed canopy % % Canopy Closure

Camera transparency method and visual

estimate of % canopy closure in fixed-area

plot (4 photos/plot)

Healthy forest canopy % trees with a healthy canopy

Dieback, discoloration of foliage, defoliation,

& vigor class estimations of trees > 10 cm

DBH (Fixed-area plot sample, USFS

Standards)

Multiple vegetative structure levels Vegetation life forms in the

understory, midstory and overstory

Abundance and size class for tree, shrub, and

% cover for herb and woody seedling

sampling (Fixed-area plot and subplots)

Understory dominated % by native

species Relative cover of native species

% cover of all herbaceous plants and woody

plants <2cm DBH (1m x 1m subplots)

Soil quality and chemistry suitable of

supporting native plants

Healthy range of pH, Organic Matter,

Macro & Micro Nutrients

Soil sample collected at each forest plot. Will

be run in the lab for analysis.

Rich forest floor Leaf litter and fine woody material on

the forest floor.

20m point intercept for groundcover and leaf

litter and duff depth, % cover in 1 x 1m plots

Limited deer herbivory, insect

defoliation

Browse on vegetation, missing leaf

tissue

% herbivory classes for understory plants and

trees/shrubs (2-10cm DBH)

Native tree regeneration Tree seedlings present in the

understory.

Seedling Percent cover & individual count (1m

x1m subplot)

Coarse woody debris inputs present Percent cover & quality CWD

% cover (Line-Intercept samples),

decomposition class for each piece (USFS

standards).

Breeding bird species composition,

levels (individuals, pairs, nests)

Breeding bird presence/activity/nest

success Breeding bird surveys

Limited encroachment, anthropogenic

alternations

Dumping piles, desire lines,

vandalism, trash

Distance and direction to paths, human use,

and anthropogenic and ecological impacts

measured within a 30m radius of plot center.

While Parks has carried out ecological inventories and natural

area management across the city since 1984, ecological

assessment data has never been collected across all natural

areas using standardized methods. In 2012, NAC contracted

with Spatial Informatics Group (SIG), in collaboration with the

University of Vermont Spatial Analysis Laboratory (UVMSAL) to

design, develop, and deploy a system capable of mapping

“natural area” vegetation types for the City of New York based

on the National Vegetation Classification Standard (NVCS)

hierarchy. Data sets and imagery included 2010 high resolution

natural color CIR aerial imagery, LiDAR data, NRCS Soil

Survey data, National Wetland Inventory (NWI) wetland data

and New York State DEC wetland mapping data. A resulting

GIS data layer is currently developed in draft form with a limited

accuracy assessment. Future ground-truthing , and vegetation

Figure 1. New York City Department of Parks and Recreation owns over 30,000 acres of parkland in New York City. 10,000

acres are considered natural areas.

Forest Regeneration and Forest

Canopy

Native and Invasive

Forest Species

Figure 4. Size class distributions of six common tree

species in Prospect Park (Brooklyn) and Van Cortlandt

Park (Bronx). This data will be used to compare to forest

patterns in reference sites and develop an indicator value

for healthy forest regeneration by ecotype.

Figure 6. Differences between the percent cover of

invasive and non-native herbaceous and woody

seedlings was found between parks. Invasive

species management is a high priority for natural

area management in New York City Parkland.

Figure 7. The relative proportion of native basal

area in forests by park, sampled in 2013

Figure 5. Canopy photos are taken at each plot. Each photo

is analyzed through software that calculates canopy

transparency. Correlations can be made between light levels

and understory dynamics in New York City forests.

The NAC Ecological Assessment framework identifies key

ecological attributes of systems, indicators of condition, and

field measurements that quantify the system’s condition --

shown above for Forest Systems (Figure 3). The resulting

indicator values define a range of conditions from stressed

and degraded systems to healthy systems. By evaluating

and ranking natural areas, the Ecological Assessment can

be used by natural area managers and planners to:

Figure 2. Draft Ecological cover map section of Jamaica

Bay including Marine Park, Brooklyn, NY. Covertype

classes are based on the National Vegetation Classification

Standard. This map was derived using an object-based

image analysis approach that integrates multiple imagery,

topographic and vector datasets

Valu

e

Threat / Vulnerability

x

x x

x

x

x

x x

x

x

x

x

Less Immediate Action

Lower Priority

Large Scale Restoration

Preserve

Conserve

Monitor

Manage

Restore

Protect x

x

x

Citywide Ecological Site Assessment

In 2013, NAC developed methodology and implemented data

collection in forests, grasslands, freshwater wetlands, and salt

marshes to characterize the health and condition of existing

habitats and communities within New York City. Protocols were

standardized and are repeatable over time to assess change.

This baseline dataset will be the first ever quantitative data

characterizing community structure, composition, and condition

across all natural communities in New York City. The

measurements include tree health metrics, vegetation species,

soil analysis, coarse woody material, and assessments of human

usage and impacts.

The resulting ecological health metrics will allow Parks to identify,

prioritize, and track park protection, management and restoration.

Study results will also allow for use as a baseline for other

targeted ecological studies.

The short and long term goals of the ecological

assessment’s comprehensive, integrated approach serve

to promote the mission of the NAC and Parks by

providing tools for the effective stewardship of the City's

natural areas to create a healthy, safe, and resilient New

York City.

Figure 3. Forest Systems Framework. This example of an assessment framework identifies key ecological attributes of systems, indicators of

condition, and field measurements that quantify the system’s condition.

Van Cortlandt Park

Trees/hectare

0 20 40 60 80 100 120

Norway maple

Sugar maple

Black birch

Ash

Black cherry

Oak

Prospect Park

Co

mm

on

Tre

e S

pecie

s

Norway maple

Sugar maple

Black birch

Ash

Black cherry

Oak

Seedlings (< 2cm DBH)

Saplings (2-10 cm DBH)

Overstory (>10cm DBH)

Average % Cover of Non-native and Invasive Species

Park

Van Cortlandt Prospect Marine Coastal Uplands

Rela

tiv

e %

Co

ver

0

20

40

60

80

relative cover of non-native species

relative cover of invasive species

% Forest Canopy Dominated by Native Trees

Park

Coastal Uplands Marine Prospect Van Cortlandt

% B

asal A

rea p

er

Park

0

20

40

60

80

100

Salt Marsh Assessment

Figures 9 and 10. Sampling Vegetation Percent Cover and Shear Vane Strength in Salt Marshes

NAC's city-wide salt marsh ecological assessment

(NACSMA) is being conducted in tandem with a

complementary analysis of salt marsh vulnerability to sea

level rise being carried out by NRG. The study protocol

utilizes vegetation sampling and soil characterization

(vane strength). Soil shear vane strength is collected in

plots containing Spartina alterniflora and Spartina patens

(two dominant marsh species in NYC marshes). Soil

shear vane strength will be used as an indicator of

belowground biomass, root health and production. This

data set will be used for guiding management and

restoration as well as creating a baseline data set for

future monitoring.

Figure 11. Data from the ecological assessment informs a prioritization tool to map the ecological values

against the threats and vulnerabilities found commonly in urban natural areas. Our goal is to use the data from

the ecological assessment to develop a structure to rate and prioritize habitats or regions within our natural

area matrix. Understanding where study areas fall along the range of values will help focus resources to

manage, protect, or restore natural areas.

Figure 8. A forest scene in Van Cortlandt

Park, Bronx, New York. This park contained

close to 90% native tree canopy.